The present invention relates to a brushless motor such as a motor for a blower unit of an air conditioning system of automotive vehicles.
Japanese Patent Provisional Publication No. 11-283478 discloses a brushless motor employed as a motor for a blower fan of an automotive air conditioner unit. Particularly, this brushless motor is arranged such that a fuse member is installed on a printed wiring board including a motor drive circuit in order to properly shut off the electric conduction. The fuse member employed in this brushless motor is constituted by a clipping end portion, an elastic intermediate portion and a soldered end portion. The fuse member is arranged such that the clipping end portion clips a first terminal portion of the printed wiring board, and the soldered end portion is soldered with a second terminal portion while the elastic intermediate portion is elastically deformed. Further, the clipping end portion is soldered with the first terminal by another solder whose melting point is higher than that of the solder for the soldered end portion.
However, such a brushless motor has been required to solve problems resulted from the arrangement of the fuse member.
It is therefore an object of the present invention to provide an improved brushless motor which performs high productivity and high reliability.
An aspect of the present invention resides in a brushless motor which comprises a stator, a rotor, a first circuit section, a second circuit section and a fuse member. The stator comprises a plurality of exciting coils which receives drive current. The rotor is rotatable relative to the stator. The first circuit section comprises a filter circuit for eliminating surges of electric power for the drive current. The first circuit section is produced on a wiring metal piece. The second circuit section comprises a control circuit for controlling magnetic field generated by the stator by controlling the drive current. The second circuit section is produced on a printed wiring board. The fuse member electrically connects the wiring metal piece of the first circuit section and a wiring pattern formed on the printed wiring board of the second circuit section. The fuse member electrically disconnects the wiring metal piece and the wiring pattern when a temperature of the wiring pattern becomes higher than a predetermined temperature.
Another aspect of the present invention resides in a brushless motor which comprises a stator, a rotor, a drive control circuit and a fuse member. The stator comprises a plurality of exciting coils of exciting coils which receives drive current. The rotor is rotatable relative to the stator. The drive control circuit supplying the drive current to the exciting coils. The drive control circuit comprises a first circuit section for eliminating surges of electric power and a second circuit section for controlling magnetic field generated by the stator by controlling drive current treated in the first circuit section. The first circuit section and the second circuit section are arranged generally in parallel with a predetermined space therebetween. The fuse member electrically connecting the first circuit section and the second circuit section. An end portion of the fuse member is welded with the first circuit section. The other end portion of the fuse member is soldered with second circuit section. The fuse member cuts an electrical connection between the first circuit section and the second circuit section when a temperature of a part of the second circuit section becomes higher than a predetermined temperature.
Another aspect of the present invention resides in a circuit structure of a brushless motor. The circuit structure comprises a drive control circuit and a fuse member. The drive control circuit supplies drive current to exciting coils of a stator of the brusless motor. The drive control circuit comprises a first circuit section for eliminating surges of electric power and a second circuit section for controlling magnetic field generated by the stator by controlling drive current passed through the first circuit section in order to control a rotation of a rotor of the brushless motor. The first and second circuit sections are three-dimensionally arranged with a predetermined space therebetween. The fuse member comprises a first end portion welded with the first circuit section, a second end portion soldered with the second circuit section and an intermediate elastic portion which is elastically deformed when the second end portion is soldered with the second circuit section. The second end portion is released from the second circuit section when solder connecting the second end portion and the second circuit section is melted.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.